A GPGPU implementation of the discrete element method applied to modeling the dynamic particulate environment inside a tumbling mill

Includes bibliographical references.Tumbling mills have been an integral part of the comminution circuit for more than a century. With the advent of better computing, discrete element modeling (DEM) has taken on the challenge to model the dynamic particulate environment inside these devices in the search for understanding and hence improving the process of the size reduction of ore. This process represents a large percentage of the energy consumption of a mine. In this work, a discrete element modeling tool was built on a GPU-based platform to perform simulations on a single commodity hardware PC. With a view to elucidating the governing mechanisms inside such devices, the extreme capabilities of the GPU are utilised to provide performance and accurate simulation. The simulation environment offers control that can never be achieved in an experimental setup. Notwithstanding, when agreement with physical experiment is achieved, confidence can be gained in the computational results. In this work the foundations and framework for a large scale GPU based discrete element modeling tool have been built with an emphasis on strict physics requirements, rather than on performance or appearance. In this regard we demonstrate the validity of the GPU implementation of a Hertz-Mindlin-based contact model

Towards realistic interactive sand : a GPU-based framework

Includes bibliographical references (leaves 147-160).Many real-time computer games contain virtual worlds built upon terrestrial landscapes, in particular, "sandy" terrains, such as deserts and beaches. These terrains often contain large quantities of granular material, including sand, soil, rubble, and gravel. Allowing other environmental elements, such as trees or bodies of water, as well as players, to interact naturally and realistically with sand, is an important milestone for achieving realism in games. In the past, game developers have resorted to approximating sand with flat. textured surfaces that are static, non-granular, and do not behave like the physical material they model. A reasonable expectation is that sand be granular in its composition and governed by the laws of physics in its behaviour. However, for a single PC user, physics-based models are too computationally expensive to simulate and animate in real-time. An alternative is to use computer clusters to handle numerically intensive simulation, but at the loss of single-user affordability and real-time interactivity. Instead, we propose a GPU-based simulation framework that exploits the massive computational parallelism of a modern GPU to achieve interactive frame rates, on a single PC. We base our method on a discrete elements approach that represents each sand granule as a rigid arrangement of particles. Our model shows highly dynamic phenomena, such as splashing and avalanching, as well as static dune formation. Moreover, by utilising standard metrics taken from granular material science, we show that the simulated sand behaves in accordance with previous numerical and experimental research. We also support general rigid bodies in the simulation by automated particle-based sampling of their surfaces. This allows sand to interact naturally with its environment without extensive modification to underlying physics engine. The generality of our physics framework also allows for real-time physically-based rigid body simulation sans sand, as demonstrated in our testing. Finally, we describe an accelerated real-time method for lighting sand that supports both self-shadowing and environmental shadowing effects